The camshaft is mounted along one side of the cylinders and drives the fuel valves through bell-cranks and push-rods. As pointed out above, two fuel valves are used. This necessitates the use of two fuel cams per cylinder, the cam noses being slightly less than 180 degrees apart for each cylinder. One feature of this engine that has merit is the variable lift of the fuel valves. The push-rod K rests on the upper surface of the rocker or bell crank R. A movement of the crank slides the push-rod roller along the rocker I?, thereby producing a change in the valve lift. The engine then has two fuel controls—variable valve lift and variable fuel charges. The variation in valve lift is under manual control only, unlike those engines using a servomotor which automatically secures the same advantages. This repre sents the method of operation. The action of the fuel pump will be discussed in the chapter devoted to fuel-pumping mechanisms.
Standard Fuel Oil Engine Co. Two-stroke-cycle Diesel Engine.—The Diesel engine manufactured by this firm is of the two-cycle type, Fig. 16A. The piston is stepped, and the scavenging air is compressed by the enlarged section of the piston.
The frame casting is massive in design. The cylinder casting fits into the bored frame cavity, which design gives a rigid support to the working cylinder. The method of fuel injection and air scavenging will be discussed in a later chapter.
Nobel Bros. Marine Diesel.—The honor of building the first commercial line of marine Diesels belongs to this Russian firm. Since the demand was for Diesels to engine the river and ferry boats, the units NObel Bros. produced were all of small powers— ranging from 50 to 200 h.p. The same firm was the first to adopt the Diesel engine to submarine boats. The Russian government leaned to the small-dimensioned sub-boats, conse quently the development of the Nobel Bros. submarine Diesel has been along the smaller units below 200 h.p., although they produced a 900 horsepower submarine Diesel prior to 1914.
Like all new apparatus the Nobel Diesel has undergone various changes in design.
Werkspoor Marine Diesel.—The first ocean-going motorship of any size equipped with a Diesel engine was the Vulcanus. This boat was a 1000-ton tank ship fitted with a 450 h.p. Werkspoor engine having cylinders 15.7 inches diameter by 31.5 inches stroke, operating at 180 r.p.m. This engine is shown in Fig. 17. Although the design necessitated an increased height, the cross head type piston was used. To eliminate the piston-heating risk, water-cooling through telescopic tubes was used. The frame was of box design and was early abandoned for the present Werkspoor frame which consists of steel columns. This later construction is illustrated in Fig. 18. This engine is being manufactured in the United States by the Midwest Engine Co., the Pacific Skandia Co. and the New York Shipbuilding and Engine Co.
Nelseco Marine New London Ship and Engine Co. manufactures both two- and four-stroke-cycle marine Diesels. Figure 19 is a cross-section of the latter type engine. This engine is built both reversing and non-reversing.
McIntosh & Seymour Marine 20 is a view of the marine Diesel manufactured by this firm, while Fig. 21 shows section and end elevations. The engine is reversible through the shifting of the camshaft, as will be dis cussed in the chapter on valve gears.
Fulton Machine Works Marine Diesel.—This company was the pioneer manufacturer of marine Diesels of small power. These units, Fig. 22, range from 32 to 100 h.p. in size and are equipped with a reversing clutch.
Lyons-Atlas Co.—The Lyons-Atlas Co. brought out a vertical Diesel, Fig. 23, from their own designs. There are several of these units in the United States. The company was reorganized as the Midwest Engine Co. and is now manufacturing the Werkspoor Diesel.
Nordberg Manufacturing Co. Diesel Engine.—This company manufactures the Carels Diesel in both two- and four-stroke cycle designs.